1. Field of the Disclosure
The disclosure relates to generating a design surface for an area of interest, for example an agricultural field, in which case the design surface promotes water drainage from soil.
2. Brief Description of Related Technology
Existing land-leveling systems are driven by lasers and global positioning satellite systems. These systems generally are automated with the ability to follow a plane of light provided by a rotating laser or a digitally designed plane using a computer and global positioning. Land-leveling is carried out for getting a desired surface and slope of the land. Proper leveling of land is crucial in agricultural farms as it ensures efficient water run-off and proper irrigation. It is also required in various other processes such as laying of railway lines, roads, parking lots and construction of buildings. Land-leveling is performed to create a surface in a field that will allow the flow of water for either irrigation or drainage. It is desirable to control the amount of water available to crops in a way that enough water is present but not enough so that the crop drowns out.
Land-leveling is carried out by cutting and filling of earth in a field to create the surface described by a laser plane or digital surface. It is important to balance the earth cut and fill so that soil or other materials do not have to be imported or exported to meet the design plan. Traditional land-leveling is done by first making relatively crude maps or cut sheets that are mathematically manipulated to achieve an earth balance. The result of these maps or cut sheets are provided to an operator who then sets his laser and machine control system to build the design. The operator can see by the machine control system display whether he needs to cut or fill in a certain area and proceeds to move the earth from high to low areas. During this process, the operator updates his cut sheet to keep track of his process. Newer systems include the ability to digitally perform mapping, design the planar surface and control earth moving and grading processes. They also record the end result as a form of verifying that the work was done properly.
The drawbacks of the aforementioned systems are that they create simple planar or multiple planed surfaces. The surface or surfaces are not smoothly integrated into a design that vertically curves into each other. They depend on an earth balance that only refers to the entire site, not portions of that site. To eliminate the abovementioned drawbacks, various systems based on ultrasound and laser have been proposed. Laser-based systems consist of a swept laser beam that forms a reference laser plane. The laser plane is so adjusted that it aligns itself with the desired terrain. The sensors attached to the blades of the scraper sense the laser plane. This information is displayed to an operator who manually adjusts the height of the implement within an acceptable tolerance range. An example of one such system is U.S. Pat. No. 4,807,131 to Clegg. Clegg teaches a system that measures the elevation of the grading blade relative to the laser plane and displays parameters such as target elevation, actual elevation and an allowable tolerance range to the operator. This enables the operator to adjust the position of the blades within the acceptable tolerance range.
However, laser-based systems suffer from a number of drawbacks. First, laser-based systems have a limited range because of the curvature of the earth, light-incoherence and temperature dependencies of the equipment. The typical range of a laser-based system is less than three thousand feet, which is very small when compared to the average size of agricultural farms. Second, laser-based systems don't provide any direct measure of accuracy and integrity of the system. Third, laser-based systems cannot be used continuously for several reasons. Fourth, wind affects the accuracy of a laser system. As these systems do not provide the horizontal position, the operator requires visible reference markers to guide the vehicle over a field. Therefore, these systems cannot be used when the visibility is low, for example at night or on a foggy day, due to the lack of markers and the blockage of the laser beam due to dust and/or fog. Due to this, an operator cannot use these systems round-the-clock. Fourth, only two-dimensional planar profiles can be achieved using laser-based systems. It is not possible to achieve curved or three-dimensional profiles.
Curved profiles are critical for proper irrigation in farm fields since the water follows the earth's geoidal shape rather than a flat planar surface. The Global Positioning System is known to provide accurate and reliable position information. Various systems based on GPS are available for carrying out farming operations like seeding, cultivating, planting and harvesting. These systems use the position information of the work implement, derived from GPS data, and the information relating to the desired topography of the field to calculate the desired position of the work implement. However, none of these systems deal with land-leveling using the Global Positioning System.
U.S. Pat. No. 5,493,494 to Henderson teaches a method and apparatus for operating compacting machinery to compact material to a desired degree of compaction. U.S. Pat. No. 5,801,967 to Henderson et al. teaches a method for calculating a volume between a previous and a current site surface for balancing. U.S. Pat. No. 6,434,462 to Bevly et al. discloses a system that controls the tractor along with the implement connected to the tractor. A central processor controls the tractor steering actuator and the implement driving actuator. Another such GPS-based system is disclosed in U.S. Pat. No. 5,764,511 to Henderson. Henderson teaches a system and method for automatically controlling the position of a work implement, which is movably connected to the vehicle. This system maintains the work implement at a pre-selected slope of cut relative to a geographic surface. Autofarm, a part of Novariant, has a system that is mainly used to do tractor steering. This system has been modified to do planar landleveling.
Though the abovementioned patents provide systems that control a tractor and an attached implement, they do not provide specific methods and modes of operation as described herein for efficient and highly accurate land-leveling. From all the abovementioned systems and patents, it is apparent that there is a need for an efficient and around-the-clock land-leveling system that can achieve three-dimensional land profiles and that has a long range and can operate in different modalities depending on the requirements of the site to be leveled. There is a need for a system that optimizes the balance of surface cut volume and fill volume of soil from the area.